The Effect of Preoperative Anemia on Complications After Total Hip Arthroplasty.

BACKGROUND: Current literature suggests that preoperative hematocrit levels may play an important role in determining risk for complications after total hip arthroplasty (THA). The purpose of this study was to determine the role of preoperative anemia status on 30-day complications after THA. METHODS: Using the National Surgical Quality Improvement Program registry from 2006 to 2016, we identified all patients who underwent primary THA. Patients were placed into 3 cohorts based on preoperative hematocrit levels (normal > 36% [N = 166,538], mild anemia 27%-36% [N = 13,214], and severe anemia <27% [N = 541]). Differences in 30-day postoperative medical complications and readmission rates were compared using bivariate and multivariate analyses. RESULTS: Multivariate logistic regression analysis identified mild anemia compared with normal hematocrit as a significant risk factor for total complications (OR: 1.46, P < .001), mortality (OR: 2.06, P < .001), renal complications (OR: 2.59, P < .001), respiratory complications (OR: 1.89, P < .001), sepsis (OR: 2.01, P < .001), wound infection (OR: 1.36, P < .001), and urinary tract infection (OR: 1.44, P < .001). Severe anemia was also risk factor, with a higher odds ratio, for total complications (OR: 1.99, P < .001). Both mild and severe anemia were significant risk factors for increased rates of perioperative blood transfusion (mild: OR, 4.04, severe: OR, 5.58), nonhome discharge (OR: 1.74, OR: 1.64), and unplanned hospital readmissions (OR: 1.42, OR: 1.66). CONCLUSION: Preoperative anemia is a significant risk for perioperative complications after primary THA. Even mild anemia can lead to significantly increased risks of mortality, medical complications, and unplanned hospital readmissions in THA. This study further supports the need for screening and preoperative intervention for patients in this at-risk group.